Buggy Grid Seeker: Project Storm Hammer
After we got done with Taito F3, Grid Seeker quickly became one of my favorites in the driver. The music is awesome, the game is awesome. Then I got to the end of stage 5, and my heart sank... It looked like someone had barfed on the screen. The game was nearly unplayable at this point...
After a full day of recon, debugging & digging I came to find out that the game itself was buggy - not the emulator.. (every emulation and video I can find about this game exhibits the problem, except in some circumstances where the bug isn't triggered aka no shooting/extra sprites on the screen when the st.5 boss blows up) Whenever the number of sprites on the screen gets really high, it just sorta forgets about some of them and leaves them stuck to the screen. (see pictures below!) Even after the game ends, and it goes back to the beginning of the attract sequence, they still remain (see last 2 pics)...
At this point I spent 2 solid days trying different methods of identifying these bad sprites and keep them from covering the screen. The only thing I have to go on here is that the stuck sprites are always at the end of each spritebank, and there is always a nice gap between the bad sprites and the good sprites, but there can be little gaps between the bad sprites. Sometime last night I finally came up with the right algo to cancel out the bad sprites, and after lots of playtesting this morning and afternoon, and several little tweaks to the algo.. we have some good results!! This feature will be toggleable in the dip settings.
p.s. the pictures: first one is normal, second is with the fix toggled on.
Enjoy & best regards,
- dink